various: add GLIB_AVAILABLE_IN_ALL everywhere else

Add the GLIB_AVAILABLE_IN_ALL annotation to all old functions (that
haven't already been annotated with the GLIB_AVAILABLE_IN_* macros or a
deprecation macro).

If we discover in the future that we cannot use only one macro on
Windows, it will be an easy sed patch to fix that.

https://bugzilla.gnome.org/show_bug.cgi?id=688681

glib/glib-private.h

@@ -54,6 +54,7 @@ typedef struct {
   /* Add other private functions here, initialize them in glib-private.c */
 } GLibPrivateVTable;
 
+GLIB_AVAILABLE_IN_ALL
 GLibPrivateVTable *glib__private__ (void);
 
 #endif /* __G_MAIN_H__ */